All in the mind

By JOHN McCRONE

The human mind appeared on Earth with astonishing suddenness. Just 70 000 years – the merest eye-blink of geological time – covers our ancestors’ transformation from smart ape to self-conscious Homo sapiens.

On the far side of the evolutionary divide stands Homo erectus, a clever beast with a brain almost as big a modern human’s, a simple tool culture and a mastery of fire – yet mentally still somehow lacking. On our own side stands Homo sapiens with the rituals and symbolic art – the cave paintings, beads and bracelets, decorative lamps and burial graves – that mark the arrival of a self-aware mind. Something sudden and dramatic must have happened, and it is this event that could be the starting point for human consciousness.

Maybe the brain merely grew beyond a critical size and lit up like a light bulb. But a more plausible cause for the great advance made by Homo sapiens was the development of modern speech or, to be precise, the ability to internalise speech and so create a controlling ‘inner voice’.

The suggestion that inner speech could be the key to understanding the special attributes of the human mind is hardly new. Even the Ancient Greeks and the 17th-century philosophers of the Enlightenment – particularly Thomas Hobbes – made reference to the possibility. And Charles Darwin wrote in The Descent of Man&colon; ‘A long and complex train of thought can no more be carried on without the aid of words, whether spoken or silent, than a long calculation without the use of figures or algebra.’ In the 1930s, the brilliant Russian psychologist Lev Vygotsky tried to rebuild …

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